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CRT Test question
Tonight I tested the 12LP4 in this set. I used a Sencore Supermack. I coudn't adjust the tracking at all (grid cutoff out of range) and no emission. Same after about 20 minutes. Then I tried raising the filament voltage by 10% to simulate a brightener. It started to barely register. Then there were a couple of jumps and it started to climb. After a few minutes I could just barely adjust the tracking and the emission was reading good. Then I lowered the filament back to 6.3VAC. The tracking was still just barely good and the emission good. The life test was o.k.
I then tried it with the B&K 465. The emission was just barely above the good line at 200ua. The grid cut off was just barely within range. The life was 2 seconds. Not impressive.
So, it might work. It might work better if a rejuvenation was tried. Therein lies my quandary. It might not be long for this world and it sounds like Hawkeye might be closing soon. I'm not going to work on this set right away. Do I try to rejuvenate it and see if it improves a lot? Do I send it to Hawkeye so I have a good known tube? I'm probably not going to be able to test it in a set before Hawkeye closes.
I do have two 12LP4As that I'm about to pick up. One not too bad and the other very questionable. I could send that one in. But it is the grey filtered face version. Having one good one and two o.k. should keep the set going for the foreseeable future.
What would you do?
John
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